What Does a Rainwater Harvesting System Cost in 2024? | Checkatrade
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Last updated on June 6th, 2023

Rainwater harvesting system cost guide

A rainwater harvesting system (RHS) usually involves the collection of rainwater on the roof, using a storage tank and pumping to direct the water where it’s needed in the home. While not usually used for drinking, water from an RHS can be used for flushing toilets, supplying washing machines and watering plants in the garden.

Rainwater harvesting can reduce your dependence on water from the mains supply. This potentially means smaller water bills. It’s also environmentally beneficial and in some cases can reduce flood risk (as run-off water goes into the RHS, not the ground).

In this guide, we’ll look at the average cost of a rainwater harvesting system in the UK.

How much does a rainwater harvesting system cost?

The cost of a rainwater harvesting system for domestic use depends on the kind of system you get. At the very simplest level, you can get a basic water butt from as little as £70. Alternatively, one with a water pump to connect it to your property for around £750.

Rainwater harvesting systemLow costHigh costAverage cost
Water butt£70£750£410
Rainwater harvesting system - domestic£2,000£3,000£2,500
Rainwater harvesting system - commercial£2,500£12,000£7,250
Installation costs (for domestic RHS)£3,000£9,000£6,000
RAM pump system--£2,000

Our costs are ballpark averages – get a local tradesperson to quote now

For a fully functioning domestic RHS, the cost will include the price of the tank, filter, pump and pipes, control unit and connectors. The average cost of rainwater harvesting systems for home use is around £2,500. This doesn’t however include installation.

If you are lucky enough to live near flowing water, you could have a RAM pump system installed. This will cost around £2,000 to install and automatically pumps water up to a water butt.

Rainwater harvesting system installation cost

Now that you’ve bought your new RHS, you need a professional contractor to install it for you. Depending on the complexity of the plumbing and pipework, plus access requirements, this can cost upwards of £3,000 for domestic systems.

A professional will make sure that the pipework for the rainwater system is clearly labelled and separated from the mains/portable water, and they will also make sure the legionella and bacteria risks have been considered.

Cost of rainwater harvesting system for businesses

A RHS for commercial use is likely to consist of a larger, more advanced system. However, smaller businesses can potentially install systems at a similar cost to domestic ones.

For larger organisations, the average commercial rainwater harvesting system cost could be as much as £12,000.

rainwater harvesting installation cost

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Where should I put the tank for my rainwater harvesting system?

Water collection tanks for rainwater harvesting are often installed just below the roof, to collect run-off. But bear in mind that tanks in this location will usually need protection from freezing.

If you’re installing the tank on the roof itself, remember that they can sometimes be unsightly as well as very heavy.

Another option is to install your tank below ground. However, excavation can be expensive and isn’t always possible on every site.

How much rainwater could I collect?

For most homes, a tank with a storage capacity of 1,500 to 2,000 litres should be adequate. This should give you enough water for your washing machine and to flush the toilet.

To work out which size tank you need, a good rule of thumb is to start at 5% of the available annual rainfall.

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Working with professional estimators, we collate cost estimates for the common home improvement and repair jobs in the UK.

All the costs are estimates only. For accurate costs for your particular requirements, you are encouraged to reach out to professional tradespeople to receive a quote for your job.

Our estimators are Chartered Members (MRICS) of the Royal Institution of Chartered Surveyors and Members of the Chartered Institute of Building (MCIOB). See full disclaimer.

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